Probing nucleon strange and charm distributions with lattice QCD
Abstract
We present the first lattice-QCD calculation of the unpolarized strange and charm parton distribution functions using large-momentum effective theory (LaMET). We use a lattice ensemble with 2+1+1 flavors of highly improved staggered quarks (HISQ) generated by MILC collaboration, with lattice spacing a ~ 0 . 12 fm and Mπ ~ 310 MeV, and clover valence fermions with two valence pion masses: 310 and 690 MeV. We use momentum-smeared sources to improve the signal up to nucleon boost momentum Pz = 2 . 18 GeV, and determine nonperturbative renormalization factors in RI/MOM scheme. We compare our lattice results with the matrix elements obtained from matching the PDFs from CT18NNLO and NNPDF3.1NNLO global fits. Our data support the assumptions of strange-antistrange and charm-anticharm symmetry that are commonly used in global PDF fits, and we find smaller than expected parton distribution at mid to small x.
US National Science Foundation Grant PHY 1653405 ``CAREER: Constraining PartonDistribution Functions for New-Physics Searches''.- Publication:
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APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- 2020
- Bibcode:
- 2020APS..DNP.EM001Z